Magnetic pulse generator ignition distributor



Sept. 13, 1966 R. FRANK 3,272,930

MAGNETIC PULSE GENERATOR IGNITION DISTRIBUTOR Filed Sept. 18, 1963 2 Sheets-Sheet 1 F/GT J 2e 1 F I+- (1 a Li-Ii? L;

ATTORNEY Sept. 13, 1966 R. K. FRANK 3,272,930

MAGNETIC PULSE GENERATOR IGNITION DISTRIBUTOR Filed Sept. 18, 1963 I 2 Sheets-Sheet 2 INVENTOR. R0515??? K. FRANK A 7' TORNEY United States Patent Mich., assignor to Warren, Mich., a cor- This invention relates generally to ignition systems for internal combustion engines, and more particularly to ignition distributors for ignition systems wherein switching of current flow to the primary winding of the ignition coil is controlled by a magnetically-pulsed semiconductor such as a transistor.

The usual ignition system for an internal combustion engine includes an ignition coil and an engine driven ignition distributor, the latter having 'a set of breaker contacts operated by an engine driven cam so that the opening and closing of the contacts controls the flow of current to the primary winding of the ignition coil. One problem with this type of ignition system is that arcing at the breaker contacts results in their deterioration so that they must be periodically replaced.

More recently, ignition systems have been proposed wherein switching of the primary coil current is accomplished by a semiconductor device such as a transistor, rather than by a set of breaker contacts. However, in such systems the transistor has to be pulsed or triggered so that its switching function is accomplished in proper timed relation with the operation of the engine. This triggering has been accomplished in one of two ways. In some systems, the prior cam-operated breaker contacts are retained, but they function only to pulse or trigger the transistor so that deterioration thereof by arcing is greatly reduced; in other systems, the camoperated breaker contacts are replaced by a so-called pulse generator comprising a pulse wheel and the magnetic pick-up device, the advantage of this triggering means being that the only moving part is the rotating pulse wheel that cannot are or wear.

Regardless of the type of transistorized system employed, a necessary portion of the system is the engine driven distributor unit having means to trigger the transistor in proper timed relation with the engine and to distribute the high voltage to the individual spark plugs. However, in every instance known to date, installation of a magnetically-pulsed transistor-controlled ignition system requires a distributor unit specially designed for the system. In other words, whether the above proposed transistorized ignition systems are intended as original equipment or as a replacement for the breaker contact type systems furnished as original equipment on existing vehicles, it has been considered necessary to replace the original distributor with another specially designed distributor, obviously an expensive proposition.

The price of these transistorized ignition systems is relatively high; thus, anything that can be done to reduce the cost thereof will greatly contribute to their acceptance by the public.

Accordingly, a general object of this invention is to inexpensively provide a distributor unit for a magnetically-pulsed, semiconductor-controlled ignition system.

A more specific object of the invention is to provide a method and apparatus for converting the usual breaker "ice contact-controlled ignition system found on most existing vehicles to a magnetically-pulsed, transistor-controlled system, but without having to replace the entire distributor unit. That is, the invention enables such a conversion to be accomplished with the existing distributor unit, regardless of its specific structure, by replacing the breaker contacts with the magnetic pick-up unit, the latter being mounted in the same manner as the replaced breaker contacts, and by applying a pulse wheel unit to .the existing cam. The conversion is completed by removing the condenser, if one is not required, and by connecting a suitable transistorized primary coil current switching unit or pulse amplifier into the system.

Another object of the invention is to provide a method and apparatus that may be suitable for converting a breaker contact-triggered type transistor-controlled ignition system to a magnetically-triggered type transistorcontr-olled system.

Still another object of the invention is to provide a magnetic pick-up device and pulse wheel devices adapted for use in a transistor-controlled type ignition system.

Other objects and advantages of the invention will become more apparent upon reference to the following specification and the accompanying drawings wherein:

FIGURE 1 is a schematic illustration of a typical breaker contact-controlled ignition system.

FIGURE 2 is a plan view of a typical distributor unit for the system shown in FIGURE 1, with the distributor cap removed.

FIGURE 3 is a schematic illustration of a typical magnetically-pulsed, transistor-controlled ignition system.

FIGURE 4 is a plan view of the distributor shown by FIGURE 2, converted according to the invention for use in the ignition system shown by FIGURE 3.

FIGURE 5 is a perspective view illustrating in greater detail the adaptor plate shown by FIGURE 4.

FIGURE 6 is a perspective view illustrating in greater detail the so-called magnetic pick-up unit shown by FIGURE 4.

FIGURE 7 is an exploded perspective view of the cam and pulse Wheel assembly shown by FIGURE 4.

FIGURE 8 is a view similar to FIGURE 7 illustrating a modification of the FIGURE 7 structure.

Referring now to the drawings in greater detail, FIG- URE 1 illustrates schematically a typical prior art breaker contact-controlled ignition system 10, including the usual battery 12, ignition switch 14, ignition coil 16 including a primary winding 18 and a secondary winding 20, a spark plug 22 for each engine cylinder, engine driven cam 23, breaker contacts 24, condenser 26 and a rotor and distributor terminals 28.

FIGURE 2 illustrates a typical distributor unit 30 for an ignition system such as that shown by FIGURE 1, the distributor unit having the rotor and distributor cap (distributor 28) removed therefrom so as to expose the usual movable breaker plate 32 on which the breaker contacts 24 and condenser 26 are mounted.

The above described ignition system is very well known to those versed in this art, and the particular ignition distributor shown by FIGURE 2 is the same as that disclosed in Larges, 3,062,929. This prior art system is shown primarily to aid in illustrating how the invention may be practiced, and no additional discussion need be given except to point out that the cam 23 for operating the breaker points is usually either formed integrally with or press-fit on a shaft 25 extending through the distributor and driven by the engine, as shown by Larges.

Every distributor unit, regardless of its specific design, has means for advancing or retarding the spark, either by rotating the breaker plate on which the breaker contacts are mounted with respect to the cam and/or by rotating the cam with respect to the distributor shaft. In FIGURE 2, the breaker contact bracket 34 is secured to the breaker plate 32, and the breaker plate is pivotably mounted for rotation about the axis of the cam 23, as shown by Larges. As is typical of all prior art distributors, the breaker plate 32 is formed with a pair of threaded holes and the breaker contact bracket 34 is formed with a pair of elongated openings 36 and 38 that may be aligned with the threaded holes in the breaker plate so that screws 40 and 42 may be employed to adjustably secure the bracket 34 on the plate 32.

FIGURE 3 illustrates schematically a typical magnetically-pulsed semiconductor-controlled ignition system 44 including a battery 46, an ignition switch 48, a pulse generating device 50 including a pulse wheel 52 and a socalled magnetic pick-up unit 54, a semiconductor-com trolled pulse amplifier and switching unit 56, an ignition coil 58 having a primary winding 60 and condenser 62 and a secondary winding 64, rotor and distributor terminal element 66 and a spark plug 68 for each engine cylinder. It will be apparent that the pulse generator 50 and rotor and distributor terminal element 66 are preferably mounted in a distributor unit generally similar to that shown by Larges, so that both the pulse wheel 52 and the rotor 67 may be driven by the distributor shaft 25.

It should be stated that the details of the pulse amplifier and switching unit 56, and its connection in the system 44 shown by FIGURE 3, form no part of this invention and may be of any suitable design, such as that shown by Johnson, 2,852,589, for example. This invention is limited to method and apparatus for conveniently and inexpensively retrofitting a distributor unit such as that shown by FIGURE 2 to one such as that shown by FIG- URE 4.

FIGURE 4 illustrates a distributor unit 70 identical to that shown by FIGURE 2, except as modified in accordance with the invention for use in the ignition system shown by FIGURE 3. Accordingly, all common elements bear identical reference numerals. It will be noted generally that the breaker contact bracket 34 and condenser 26 of FIGURE 2 have been removed, the bracket 34 having been replaced by a magnetic pick-up unit 72 (see FIG- URE 6) secured to an adaptor plate 74 (see FIGURE which, in turn, is secured to the breaker plate 32. Additionally, a pulse wheel assembly 76 has been fitted on the cam 23.

Referring now to FIGURE 5, it will be seen that the adaptor plate 74 is formed to provide a recessed portion 78 so as to not interfere with the shaft 25 and cam 23 when it is secured to the breaker plate 32. For purposes of retrofitting the particular distributor shown'by FIG- URE 2, the adaptor plate 74 has openings 80 and 82 formed therein so that it may be secured to the breaker plate 32 by means of screws 84 and 86, respectively, screw 84 engaging the same threaded opening in breaker plate 32 as that engaged by screw 40 in FIGURE 2. and screw 86 engaging the same threaded opening in breaker plate 32 as screw 90 employed to secure the condenser in FIGURE 2. It will thus be apparent that a generally similar adaptor plate may be provided for any prior art distributor; as a practical matter, it has been found that a set of only about ten such adaptor plates of slightly different design will cover the field. The plate 74 is also formed with a pair of threaded openings 92 and 94, the center-line distance of which is preferably identical but the exact location of which may be different for the set of adaptor plates referred to above.

With the above adaptor plate construction in mind and referring now to FIGURE 6, it will be seen that the magnetic pick-up unit 72 is assembled on a bracket 96, which is very similar to bracket 34 on which the breaker contacts 24 are assembled. The bracket 96 is formed with a pair of elongated openings 98 and 100, the center-line distance of which is the same as the center-line distance between threaded openings 92 and 94 formed in the adaptor plate 74, and a pair of up-turned flanges 102 and 104. A permanent magnet 106 and a core member 108 are secured to the flange 102 in any suitable manner such as riveting, the core member 108 being formed to provide a portion 110 extending across the bracket. A suitably wound coil 112 is positioned over the inwardly extending portion 110 so that it becomes a core for the coil, one end of the coil being connected to the bracket 96 as a ground and the other end of the coil being connected to an insulated post on the other flange 104, the post having a lead 114 extending therefrom adapted to be connected to the pulse amplifier and switching unit 56.

As seen in FIGURES 4 and 6, the bracket 96 may be adjustably secured to the adaptor plate 74 by means of screws 116 and 118. It will likewise be seen that a universal design of adjustable magnetic pick-up unit 72, when used in combination with a suitable adaptor plate 74, may be assembled on any prior art distributor unit for converting the same to use in an ignition system such as that shown by FIGURE 3, the adaptor plate and the adjustability of the unit 72 providing proper registration of rotor 67. It would, of course, also be possible to provide proper rotor registration by eliminating the adaptor plates and designing a different magnetic pick-up for each distributor application, the magnetic pick-up being adjustably mounted directly on the breaker plate like the previously employed breaker contacts.

In comparing FIGURES 2 and 4, it will be noted that the shaft 25 and cam 23 have not been disturbed. Rather, the pulse wheel assembly 76 has been fitted on the cam 23, the pulse wheel assembly 76 being shown more clearly in FIGURE 7. The assembly 76 generally comprises a sleeve-like member 120 to be fitted over the cam 23 and a spider-like member 122 to be fitted over the sleeve 120. Member 120 may be formed of any suitable material; in the embodiment shown, it may be formed by diecasting a suitable plastic or by a sintered metal process to provide a cylindrical body having a hexagonal axial opening adapting the same to be secured to the cam by a press-fit or by other suitable means such as a set screw. The sleeve member 120 is additionally formed on the outer surface thereof with six axially extending grooves 121 adapted to receive a similar number of prongs 124 extending from the stamped or otherwise suitably formed member 122. With the sleeve 120 and member 122 assembled on the cam 23 as shown in FIGURE 4 and assuming that the member 122 is made from a material such as iron or steel, it will be apparent that one complete revolution of the cam 23'will generate six distinct positive voltage pulses in the coil 112, one pulse each time one of the prongs 124 passes the adjacent end of the core member, sufficient to trigger the semiconductor employed to switch the primary coil current.

At this point, it should be recalled that the usual prior art ignition system shown by FIGURE 1 creates a spark at a plug 22 each time that a lobe or high point on the cam 23 opens contacts 24. In FIGURES 4 and 7 it will be noted that the prongs 124 are not located at the cam lobes, but are offset slightly. This offset is due to the fact that it is desirable to employ a universal magnetic pick-up design and a series of adaptor plates. However,

even with a suitable adapotor plate, it may not always be possible to locate the magnetic pick-up in exactly the same relation with respect to the cam as the replaced breaker contacts. The offset, if any, corrects for this, the important point being that the magnetic pulse occur at the same time in the converted distributor 70 as the contacts opened in the prior distributor 30. Thus, if a distributor 30 is properly timed before removal from the engine for conversion, it will be properly timed after conversion if reinstalled in the engine in the same position.

FIGURE 8 illustrates a modified pulse wheel assembly 126 in which the sleeve member 120 of FIGURE 7 is replaced by a neoprene or other suitable elastic cylinder 128 which is adapted to be stretched over the cam 23, and over which the spider member 122 may be forced. In this modification, the wall thickness of the member 128 would be such that each of the prongs 124 of the spider member 122 would depress the outer surface thereof radially inwardly, giving the same positioning and retaining effect .as the grooves 121 formed in member 120.

The pulse wheel assembly shown is employed to provide more distinct pulse signals than would be provided with the use of the cam alone. While they vary in shape, most cams employed in prior distributors to open the breaker contacts comprise a generally circular body having 4, 6 or 8 high points or lobes connected smoothly by straight line (see FIGURE 2) or convex portions so as not to cause excessive wear of the cam follower or rubbing block attached to the movable arm of the breaker contacts, and they do not have sufficient change in contour between the lobes to constitute a pulse wheel capable of providing pulses of proper magnitude and shape.

It will be apparent that any structure equivalent to that shown in FIGURES 7 and 8 and adapted to be fitted over the cam and to give more distinct and properly shaped pulse signals may be employed. It is also recognized that the cam itself could be modified or that a new distributor shaft having a specially designed pulse wheel could be employed with the magnetic pick-up contemplated by the invention,

Assuming now that the owner of a vehicle having an ignition system such as that shown by FIGURES 1 and 2 wishes to convert it to the system shown by FIGURE 3, it is apparent that he could purchase a conversion kit contemplated by the invention, the kit containing whatever is required for the pulse amplifier and switching unit 56, possibly a more suitable coil 58, a magnetic pick-up 72, a suitable adaptor plate 74 and a pulse wheel assembly equivalent to assembly 76. Where the bracket 96 is identical to the bracket 34, as it is contemplated may be the case in some instances, an adaptor plate may not be required, in which event the previously mentioned offset construction of the pulse wheel may not be necessary. It will be noted that a distributor unit 30, or even a new shaft 25, is not required.

Having purchased the above kit, the owner would merely remove the distributor unit 30 from the engine and then remove the breaker contact bracket 34 and the condenser 26. Note, however, that in most instances removing the distributor from the engine is not a necessity. He would then mount the magnetic pick-up bracket 96 on the adaptor plate 74 and secure the adaptor plate to the breaker plate 32. Next, the sleeve member 120 would be press-fit or otherwise secured on the cam 23 and the spider member 122 would be applied over the sleeve 120, the opening 125 in the spider member allowing it to pass over any portion of the shaft 25 that extends beyond the cam 23. Since the position of the prongs 124 in the grooves 121 with respect to the lobes of the cam 23 would be properly offset, if the olfset is required for the particular distributor unit being modified, replacement of the distributor in its original position on the engine would assure proper timing. Finally, the screws 116 and 118 would be loosened and the distance between the core 110 and any one of the prongs 124 would be adjusted to specification, by moving the bracket 96 in either direction along a diameter of the cam 23, and the screws 116 and 118 tightened. The conversion would then be completed by properly mounting and electrically connecting the pulse amplifier and switching unit 56 and new coil 58, if one is required; however, as previously stated, the unit 56 and coil constitute no part of this invention.

From the above description, it is apparent that conversion from any FIGURE 1 type ignition system to a FIG- URE 3 ignition system may be accomplished easily and quickly and at a minimum expense. The savings effected by salvaging a major portion of the prior distributor 30 may, if desired, be used to improve the quality of the electronic and other components of the unit 56, which is an important part of the FIGURE 3 system, the ultimate result being a superior overall system which can be manufactured at a competitive cost.

While but one modification has been shown and described, it is apparent that other modifications are possible within the scope of the invention, and no limitations are intended except as recited in the appended claims.

What I claim as my invention is:

1. A pulse wheel assembly for converting a breaker contact type ignition distributor having a multi-lobe cam formed on the shaft thereof to a magnetic pulse type distributor, said pulse wheel assembly comprising a resilient tubular member adapted to be applied to the outer periphery of the cam by stretching the same over said cam, and a magnetically permeable member having a generally circular portion and equally spaced prongs extending axially from the periphery thereof, said permeable member being adapted to be applied over the said resilient member once said resilient member has been applied to the outer periphery of the cam and in a manner so that said generally circular portion is parallel to an end face of the cam and so that said prongs retain said permeable member on the cam by compression of said resilient member.

2. An ignition distributor of the type wherein current flow to the primary winding of the ignition coil is controlled by a semi-conductor device triggered by a pulse generator operated by a distributor, comprising a housing, a shaft mounted for rotation in said housing, a multilobed cam provided on said shaft, a pulse Wheel fitted on said cam, said pulse wheel being formed from a nonmagnetic material and having as many magnetically permeable segments near the outer periphery thereof as there are lobes on said cam, and a device including a magnet and a coil having a core mounted in said housing in a position adjacent said pulse whee-l so that a voltage signal occurs when a segment of said pulse wheel passes said core.

3. An ignition distributor of the type wherein current flow to the primary winding of the ignition coil is controlled by a semi-conductor device triggered by a pulse generator operated by a distributor, comprising a housing, a shaft mounted for rotation in said housing, a multi-lobed cam provided on said shaft, a segmented pulse wheel fitted on said cam, there being as many magnetically permeable segments near the outer periphery of said pulse wheel as there are l'obes on said cam and a device including a magnet and a coil having a core mounted in said housing in a position adjacent said pulse wheel so that a voltage signal occurs when a segment of said pulse wheel passes said core.

4. A converted ignition distributor of the type wherein current flow to a primary winding of the ignition coil is controlled by a semi-conductor device triggered by a pulse generator operated by a distributor, comprising a housing, a shaft mounted for rotation in said housing, a multi-lobed cam provided on said shaft, said cam having been formerly used in the making and breaking of conventional breaker contacts, a pulse wheel fitted on said cam, a plurality of magnetically permeable segments provided near the outer periphery of said pulse wheel and a device including a magnet and a coil having a core mounted in said housing in a position adjacent said pulse wheel so that a voltage signal occurs when a segment of said pulse wheel passes said core.

5. An ignition distributor of the type wherein current flow to the primary winding of the ignition coil is controlled by a semi-conductor device triggered by a pulse generator operated by a distributor, comprising a housing, a shaft mounted for rotation in said housing, a m-u-lti-lobed cam provided on said shaft, a pulse wheel fitted on said cam, said pulse wheel being formed from a non-magnetic material and having as many magnetically permeable segments near the outer periphery thereof as there are lobes on said 0am, and a magnetic field generating means mounted in said housing in a position adjacent to and at all times spaced apart from of said pulse whee-1 passes said device.

References Cited by the Examiner UNITED STATES PATENTS Aske 20087 Wolrab 20019 X Heutten 20087 X Race.

BERNARD A. GILHEANY, Primary Examiner.

said pulse wheel so that a signal occurs when a segment 10 ROBERT K. SOHAEFER, H. M. FLECK,

Assistant Examiners. 

1. A PULSE WHEEL ASSEMBLY FOR CONVERTING A BREAKER CONTACT TYPE IGNITION DISTRIBUTER HAVING A MULTI-LOBE CAM FORMED ON THE SHAFT THEREOF TO A MAGNETIC PULSE TYPE DISTRIBUTER, SAID PULSE WHEEL ASSEMBLY COMPRISING A RESILIENT TUBULAR MEMBER ADAPTED TO BE APPLIED TO THE OUTER PERIPHERY OF THE CAM BY STRETCHING THE SAME OVER SAID CAM, AND A MAGNETICALLY PERMEABLE MEMBER HAVING A GENERALLY CIRCULAR PORTION AND EQUALLY SPACED PRONGS EXTENDING AXIALLY FROM THE PERIPHERY THEREOF, SAID PERMEABLE MEMBER BEING ADAPTED TO BE APPLIED OVER THE SAID RESILIENT MEMBER ONCE SAID RESILIENT MEMBER HAS BEEN APPLIED TO THE OUTER PERIPHERY OF THE CAM AND IN A MANNER SO THAT SAID GENERALLY CIRCULAR PORTION IS PARALLEL TO AN END FACE OF THE CAM AND SO THAT SAID PRONGS RETAIN SAID PERMEABLE MEMBER ON THE CAM BY COMPRESSION OF SAID RESILIENT MEMBER. 